Metal holders that are subject to the process of this invention are especially, but not exclusively, those made of aluminium, its alloys, steel or other suitable materials from which bottles for the beverage and food sectors or for technical use are made.
The primitive shape of these metal holders is basically cylindrical and it is later shaped according to known procedures and technologies; even the tapering process of the upper end of these metal bodies or holders is made according to known technologies and, hence, is not described.
The foregoing metal holders are deformed close to their upper end, to make the edge or collar described in this process, preferably at the final stages of the working process, that is after having undergone the multiple operating stages for the shaping of the external surface and/or the embossing/debossing operating stages, that is those processing stages that create over preset areas of the side surface shaped marks, grooves and other patterns of various shapes defined by hollow and/or embossed sectors.
These same metal holders or bodies, possibly painted and/or lithographed, are basically fed on a tapering machine which, in a preferential embodiment which is not meant to provide any limitation, is such as to include at least a rotating table featuring intermittent movement, with multiple stations equipped with pliers or similar tools for the temporary fastening of bodies and at least an opposed plate provided with an alternating shifting motion on which are several tools and/or mandrels, which are meant to intervene at pre-set sequences on the extruded deep-drawn and deep-drawn/wire-drawn bodies in order to accomplish the progressive stages of initial deformation and later tapering of the upper end.
In order to perform both the tapering and the embossing/debossing operations, the metal holder processing machine avails of holder gripping and stabilization means of known type which, wherefore, are not described herein.
In recent times the market has revealed greater interest for metal holders featuring structures that are similar to those that are traditionally peculiar to holders made of other materials, such as plastic or glass, hence it has become important to provide these new holders, basically intended to serve the beverage market, with closure types that are similar to those of plastic (PET) or glass holders.
Glass holders, for instance, though featuring aesthetic values that definitely surpass those of traditional metal holders or bodies, present the disadvantage of weighing too much, of being easily subject to breakage and entailing high production costs; vice versa, the metal holder, in addition to the required level of hygiene, can also ensure greater lightness compared to glass, is infrangible, easily disposable and recycled. Nevertheless, as the dealing is with bottles or holders made of metal, it is important that the working of the upper end of the mentioned bottle results in the performance of an edge that is shaped in such a manner as not to present cutting edges that may irritate or even bring about potential hazards to the user who draws the holder close to his mouth in order to drink straight from it.
As far as holders made of metal are concerned, there are various types of closures, such as, for instance, the application of a “crown” cap, a “ring-pull” cap or a “screw” cap; to obtain these different types of closures, different and specific types of working need to be performed on the metal holder. The application of the “crown” cap and of the “ring-pull” cap requires the upper end of the metal holder to have an edge or collar, to be made by folding or turning outwardly the inner wall or surface of the opening.
However, the shape of the metal holder edge or collar that accommodates a “crown” cap is different from that for the application of the “ring-pull” cap; the making of the two different edges also entails a sequence of different operations to be performed on the holder and the application on the tapering machine of replacement tools and mandrels that are fit to work the top edge of the holders themselves. This requires longer machine tooling time with ensuing more or less extended machine downtime.